KAC Citrus Entomology
University of California
KAC Citrus Entomology

Monitoring

Summer-Fall Leaf Sample

Copy of DSCN1398
Sampling should be done when the scales have fully emerged and are infesting the leaves (July-September).  Collect the leaves from the shady part of the NE corner of the tree. 
threescales2
Be sure to carry a hand lens, especially in July when the nymphs are very tiny, to determine if the scales are live or dead.  High summer heat can kill many of the scales.  Dead scales are dried out (left). Dying scales may look puffed up or are starting to darken (middle).  Count only the healthy looking live scales (right).

Treatment Threshold

To determine if the population of citricola scale has reached the treatment threshold, collect one leaf from the NE corner of each of 25 trees in 4 evenly spaced rows in the orchard (a total of 100 leaves per orchard).  For each row, count the number of leaves out of 25 that have at least one live nymph and enter that number in the table below. 
Row

No. of leaves
with live citricola
(place count here)

1-4 leaves
don't treat
(if true, check box)

5-12 leaves
consider treating
(if true, check box)

13-25 leaves
treat this year
(if true, check box)

1        
2        
3        
4        

If any row has a box checked 'treat this year' then treat the whole orchard.
If any row has a box checked 'consider treating', then it is a judgment call.

For more information on sampling and evaluating scales see Citricola Scale Citrograph Article 1999.

For more information

For more detailed information on monitoring citricola scale consult the UC IPM Guidelines for Citrus: Citricola Scale.
Webmaster Email: eegraftoncardwell@ucanr.edu